The present invention relates to a process of ozone production and, more specifically, to high frequency ozonizers.
Ozone is a very important product having a wide range of application in various branches of industry. For example, ozone can be used for the purification of potable water and industrial effluents, and for the removal of nitrogen oxide and other toxic gases from the environment. Ozone can also be used in various branches of chemical production, for example in chemical production processes based on organic and non-organic chemicals, in metallurgy etc.
Known installations for the synthesis of ozone comprise a dielectric in the discharge gap thereof. In accordance with the type of system used for cooling the dielectric, these installations are subdivided into installations without intensive cooling of the dielectric, preferably having an air-cooled dielectric, and installations having an intensive liquid cooling system. The installations without intensive liquid cooling are intended for operation at frequencies of 50-60 Hz. The working capacity of such ozonizers is comparatively low. The installations having an intensive liquid cooling system for the dielectric are capable of operating at increased frequencies of about 1000 Hz and have a higher working capacity which can be further increased in proportion to the frequency.
Known in the art are a number of embodiments of ozonizers having a liquid cooling system for both electrodes.
These ozonizers have a common housing and comprise coaxially arranged tubular metal low voltage and high voltage electrodes. The conjugate surfaces of said electrodes, coated with a dielectric, form a discharge gap in which the electric discharge and the ozone generating reaction take place. The low voltage electrodes are cooled with a flow through of cooling liquid, which flows through the space formed by the housing and the low voltage electrode. The high voltage electrodes are cooled with a flow through of gas or liquid coming into the tubular spaces between the electrodes from the input manifold. This gas or liquid is then discharged from said spaces into the output manifold, which is analogous to the input manifold, provided the cooling liquid does not cause a short circuit between the low voltage and high voltage electrodes.
The main disadvantage of this embodiment of an ozonizer is the complexity of replacement of faulty electrodes.
Another embodiment is an ozonizer comprising a housing with low voltage and high voltage electrodes coaxially arranged therein.
The low voltage electrode consists of a metal pipe with a dielectric attached to its inner surface, and a metal tubular casing. The space formed by the casing and the metal pipe is provided with corrugated metal.
The high voltage electrode is closed at one end and is rigidly secured to a high voltage insulator. The space formed by the conjugate surfaces of the dielectric of the low voltage electrode and the metal surface of the high voltage electrode, form a discharge gap in which ozone generating reaction takes place.
The low voltage electrode is cooled by a liquid which flows in the space formed by the casing of the electrode and the housing of the ozonizer. Heat from the dielectric is removed through a metal pipe secured on the dielectric and also through the metal corrugations. The casing of the high voltage electrode, as well as the housing, is fastened between the end covers of the ozonizer.
The high voltage electrode has no direct flow through cooling. The inflow of the cooling liquid is provided through a special pipe arranged along the axis of the electrode. The ozonizer is cooled by oil supplied to the electrodes by a special pump.
It should be noted that the above system provides inadequate cooling of the dielectric. This is a result of the heat from the dielectric being discharged through the metal corrugations. The heat dissipating surface of these corrugations is small since the metal pipe secured on the dielectric has no direct contact with the cooling liquid.
The degree of cooling of the high voltage electrode is also inadequate, owing to the low flow velocity of the cooling liquid along the surface of the electrode. This liquid is oil rather than water.
Known in the art is another embodiment of a high frequency ozonizer, wherein several ozonizing elements, consisting of glass low voltage and metal high voltage tubular electrodes, are secured in a common metal casing. The conjugate surfaces of these electrodes form a discharge gap in which the ozone generating reaction takes place during electric discharge.
The low voltage electrodes are cooled directly with a flow of liquid, preferably water, flowing in the space formed by the casing of the ozonizer and the surfaces of the electrodes. The high voltage tubular electrodes, having varying cross-sections, are mounted in manifolds through which the cooling liquid is supplied and removed. The coolant, which may be water, is supplied to the manifolds and removed from these manifolds through long pipelines made of a dielectric material. The manifolds are secured to the bottom of the ozonizer casing by means of cylinder-shaped gas chambers.
We must point out the complexity of centering the many high voltage electrodes in the ozonizer relative to the low voltage electrodes. This centering is required to provide for an even discharge gap along the whole length of the ozonizing element. Since the electrodes are secured in the manifolds, it is necessary to center the manifolds relative to the ozonizer casing. Besides, the dismantling of the ozonizer for repair or for replacing the dielectric is a rather complicated procedure.
The object of the present invention is to provide a high-frequency, high capacity ozonizer having metal electrodes coated with a dielectric, which may be easily dismantled into high voltage and low voltage units. Such a feature considerably simplifies the mounting and dismantling of the ozonizer for preventive inspection and repair.